Distribution Characteristics and Controlling Factors of Heavy Metals in Surface Sediments from the Bay-Island-Estuary System (BIES): A Case Study in Coastal Waters of Fujian Province, China

Based on the contents of six heavy metal elements in surface sediments from coastal areas of Fujian Province, the distribution characteristics and controlling factors of six heavy metals in a bay-island-estuary system (BIES) were studied. This paper focuses on the influence of the hydrodynamic environment, and systematically discusses how grain size compositions, chemical environment, tidal current, ocean circulation and human activities influence the distribution and transportation of the heavy metals. The results indicated that the distribution and migration of Cu, Pb, Zn and Cr elements were mainly controlled by natural factors such as regional geological background, grain size compositions, and tidal residual currents. In contrast, As and Hg was mainly affected by human factors such as agriculture and industrial manufacturing. In the BIES, where the chemical environment exerted limited influence, the accumulation and migration of heavy metals are mainly influenced by human activities and enhanced by estuary processes as well as the complex sedimentary dynamic environment caused by many bays and islands.